Credits to: http://www.ericasweettooth.com/2012/03/salted-caramel-shortbread-fbf-orlando.html
for the shortbread layer:
10 tbsp unsalted butter, at room temperature
1/2 cup sugar
1/2 tsp salt
1 egg yolk
1-2/3 cups flour
for the caramel:
1 cup unsalted butter
1 cup light brown sugar
3/4 cup light corn syrup
2 tsp sea salt, plus more for sprinkling on top
4 tbsp sugar
4 tbsp heavy cream
1-1/2 tsp vanilla extract
Line an 8×8″ pan with parchment paper, leaving some hanging over the sides to make removal easier.
In a large bowl, combine the butter, sugar, and salt with a pastry cutter or fork. Add the egg yolk and continue mixing.
Add the flour and use your hands to combine the dough until coarse crumbs form. Transfer the dough into the prepared pan and press it down into one even layer.
Refrigerate for 30 minutes. Preheat oven to 350 degrees and bake for 25 minutes, until slightly golden brown. Set aside to cool.
For the caramel, combine the butter, brown sugar, corn syrup, salt, sugar, and heavy cream. Bring to a boil and stir for about 5-10 minutes until caramel reaches the “soft ball stage” at around 230 degrees.
Remove from heat, stir in the vanilla and pour caramel over the shortbread.
Refrigerate for at least 3 hours, then sprinkle with sea salt and cut into squares. Store caramels in the fridge until you’re ready to eat them.